Normalized extent of the evanescent region as a function of q, for typical values of β. Solid lines represent the predictions of the model in the cases of Type-a very thin evanescent regions and thick Type-b evanescent regions for q ≳ 0.15 and q ≲ 0.13, respectively. The dashed lines correspond to the predictions for thick Type-a evanescent regions for q ≳ 0.15. The blue rectangle indicates the estimated domain of the transition regime between Type-a and Type-b evanescent regions on the RGB. Typical values (vertical dash-dotted lines) and their error bars (vertical gray strips) are represented for subgiant (SG), young red giant (YR), evolved red giant (ER) and red clump (RC) stars (see main text).